A thermal compression bonding process is a process used to assemble/package a flip chip, die or semiconductor device to a packaging substrate. Such a flip chip is often referred to as a thermal compression flip chip (TCFC). FIG. 1 illustrates an example of a package that includes a chip/die coupled to a substrate using a thermal compression bonding process. As shown in FIG. 1, a package 100 includes a die/chip 102 that is coupled to a substrate 104. There are several electrical connections 106 and a non-conducting paste (NCP) 108 between the chip 102 and the substrate 104. The electrical connections may be defined by under bump metallization (UBM) structures (e.g., UBM structure 110), solder (e.g., solder 112) and traces (e.g., trace 114). The NCP 108 provides a protective layer that covers the electrical connections between the chip 102 and the substrate 104.
FIG. 2 illustrates an example of how a chip/die may be assembled to a package by using a thermal compression bonding process. Specifically, FIG. 2 illustrates a package 200 and a die 202. The package 202 includes a packaging substrate 204 and several traces 206a-c. FIG. 2 also illustrates a non conductive paste (NCP) 208, which is usually dispensed on top of the traces 206a-c before thermo-compression is done. The NCP 208 may have fluxing capabilities, which means the NCP 208 may be capable of removing oxide from materials (e.g., remove oxide from bumps and/or traces). Oxide is a material layer that may be formed on the surface of an underlying material when the underlying material is exposed to air, water and/or other chemicals. The die 200 includes several bumps 210a-c. Each of the bumps 204a-c respectively includes copper pillars 212a-c and may also include solders 214a-c. 
During the thermal compression bonding process a few things may happen that can cause the assembly of the die to the package to fail. In one instance, the solder (e.g., solder 214b) may wet excessively with the side of the bump (e.g., bump 210b) on the die side. Normally, oxide on a material prevents solder to wet (flow and attach) to the material. However, when at least some of the oxide is removed, the solder may wet to the material. During the thermal compression bonding process, excessive wetting of the side of the bump may happen because the NCP 208 that is used removes oxide from the bump (e.g., from the copper pillar), which allows solder to wet to the side of the pillar. Excessive wetting can also occur when the bump is covered with a gold based surface, which has a highly wettable property. This wetting of the side of the pillar may lead to joint starvation. When joint starvation occurs, the resulting connection/joint between the bump, the solder and the trace is open or poor. In an open joint, there is no connection between the bump, the solder and the trace. That is there is a gap between the bump and the trace in some implementations. In a poor joint, the connection between the bump, the solder and the trace is very weak and will likely fail over the life of the die and/or package.
FIG. 3 illustrates a die assembled to a package after a thermal compression bonding process. Specifically, FIG. 3 illustrates the package 200 and the die 202 of FIG. 2 after a thermal compression bonding process. As shown in FIG. 3, the bump 210a is coupled to the trace 206a. Similarly, the bump 210b is coupled to the trace 206b, and the bump 210c is coupled to the trace 206c. As shown in FIG. 3, there is no joint between the bump 210b and the trace 206b, as illustrated by the fact that the most of the solder 214b is on the trace 206b (e.g., because of excessive wetting of the trace 206b) and some of the solder 214b is on the bump 210b, with a gap between the bump 210b and the trace 206b. In contrast, there is a joint between the bump 210a and the trace 206a. Moreover, the solder 214a is in contact with both the trace 206a and the bump 210a without any gap in the solder 214a. 
Therefore, there is a need for an improved design to ensure solid joints are created between solder and trace. In addition, such a design will also reduce excessive wetting of traces and/or bumps.